L1 Lagrangian Point.

Does anyone know how long SOHO and ACE took to get to the L1 lagrangian point. It is in average 1.496 million km away, Im wondering how fast a human space flight servicing mission would take. Also if it is possible to send it for a long mission seeing that the radiation dosage increases and temperature of space craft increases too.

Not sure how long it took, but I do know that none of the recent spacecraft are designed to be human serviceable and if they break then they will be retired. Having a space craft that uses or requires human serviceablity (i.e. Hubble) turned into something of a nightmare, which most people would rather avoid. It turns out that for the same cost of making something human serviceable you can build several non-serviceable spacecraft.

Exactly what I thought. In essence sending a unmanned space craft will certainly be cheaper than a servicing mission, but does this mean we should never send Astronauts to space. The ACE is due for retirement on 2024. Could it ever be viable to go to the L1 point assuming the cost of launching into orbit is significantly reduced. I'd like to think that astronauts can do a more efficient job than just the robotics in an unmanned space craft.

Could anyone tell me what the space shuttle radiation shielding is? And how much dosage of radiation per sec or day do astronauts receive in orbit?